Nestable, rigid, planar air filter frame

Abstract

A nestable frame for planar air filters or other screen-like planar structures. The nestable frame provides all of the following desirable properties at once: 1. Simple manufacturing and assembly process, 2. Simple design, 3. Enhanced structural rigidity, 4. Significant space-savings during storage and transport, and 5. Simple handling. The filter frame comprises an upper and a lower frame portion with a first leg each, where the peripheral edge of the filter media is clampingly engaged between the first leg of the upper frame portion and the first leg of the lower frame portion. From the first leg, both frame portions extend outwardly with a second leg at an obtuse angle. The frame portions are connected at the outer ends of their second legs with a connecting leg. Alternative embodiments contain straight connection legs at different angles, curved connection legs or a multitude of connection legs, oriented to the outside of the frame or collapsed inwardly into the frame, for various purposes. Yet alternative embodiments include various values for the obtuse angles between the first and second legs of the upper and lower frame portion. While same angles between corresponding legs of both frame portions may allow for easier design of the frame, a larger angle in the lower frame portion may allow for greater rigidity of the frame at the level of the plane of the filter medium.

1 . A filter frame having a cross-section comprising:
 a. an upper, middle, and a lower frame portion;   b. wherein the upper frame portion comprises a first leg and a second leg extending at a first obtuse angle from the first leg;   c. wherein the lower frame portion comprises a first leg and a second leg extending at a second obtuse angle from the first leg;   d. wherein the middle frame portion comprises at least one leg, the at least one leg connecting the second leg of the upper frame portion to the second leg of the lower frame portion;   e. wherein the first legs of both the upper and lower frame portions are parallel to each other; and   f. wherein the at least one leg of the middle frame portion and the second legs of the upper and lower frame portions define a hollow space.   
   
   
       2 . The filter frame of  claim 1 , wherein the first obtuse angle is approximately equivalent to the second obtuse angle. 
   
   
       3 . The filter frame of  claim 1 , wherein the first obtuse angle is smaller than the second obtuse angle. 
   
   
       4 . The filter frame of  claim 1 , wherein the second obtuse angle is larger than the first obtuse angle. 
   
   
       5 . The filter frame of  claim 1 , wherein the at least one leg of the middle frame portion is one leg that is approximately perpendicular to the first leg of the upper frame portion. 
   
   
       6 . The filter frame of  claim 1 , wherein the at least one leg of the middle frame portion is one leg that is approximately parallel to the first leg of the upper frame portion. 
   
   
       7 . The filter frame of  claim 1 , wherein the at least one leg of the middle frame portion is one leg that is angled with respect to the first leg of the upper frame portion. 
   
   
       8 . The filter frame of  claim 1 , wherein the at least one leg of the middle frame portion is comprised of three legs. 
   
   
       9 . The filter frame of  claim 1 , wherein the at least one leg of the middle frame portion is comprised of a curved leg. 
   
   
       10 . The filter frame of  claim 1 , wherein the at least one leg of the middle frame portion is comprised of a convex curved leg. 
   
   
       11 . The filter frame of  claim 1 , wherein the at least one leg of the middle frame portion is comprised of a concave curved leg. 
   
   
       12 . The filter frame of  claim 1 , wherein the upper, middle, and lower frame portions are made of one contiguous piece of material. 
   
   
       13 . The filter comprising:
 a. a filter medium having at least one peripheral edge and first and second opposite major faces; and   b. a frame member surrounding the at least one peripheral edge of the filter medium panel, the frame having a cross-section comprising:
 i. an upper, middle, and a lower frame portion; 
 ii. wherein the upper frame portion comprises a first leg and a second leg extending at a first obtuse angle from the first leg; 
 iii. wherein the lower frame portion comprises a first leg and a second leg extending at a second obtuse angle from the first leg; 
 iv. wherein the middle frame portion comprises at least one leg, the at least one leg connecting the second leg of the upper frame portion to the second leg of the lower frame portion; 
 v. wherein the first legs of both the upper and lower frame portions are parallel to each other; and 
 vi. wherein the at least one leg of the middle frame portion and the second legs of the upper and lower frame portions define a hollow space. 
   
   
   
       14 . The filter of  claim 13 , wherein the second obtuse angle is larger than the first obtuse angle. 
   
   
       15 . The filter of  claim 13 , wherein the frame member is made from one contiguous piece of material.